Low Dose Iodinated Contrast Material and Radiation for Virtual Monochromatic Imaging in Craniocervical Dual-Layer Spectral Detector Computed Tomography Angiography: A Prospective and Randomized Study

Abstract

Rationale and ObjectivesTo investigate the feasibility of virtual monochromatic imaging (VMI) of dual-layer spectral detector computed tomography (SDCT) to reduce iodinated contrast material and radiation dose in craniocervical computed tomography angiography (CTA). Materials and MethodsA total of 280 consecutively selected patients performed craniocervical CTA with SDCT were prospectively selected and randomly divided into four groups (A, DoseRight index (DRI) 31, iopromide 370mgI/ml, volume 0.8ml/kg; B, DRI 26, iopromide 370mgI/ml, volume 0.4ml/kg; C, DRI 26, ioversol 320mgI/ml, volume 0.4ml/kg; D, DRI 26, iohexol 300mgI/ml, volume 0.4ml/kg). 50-70 kiloelectron volts (keV) VMIs in group B were reconstructed and compared with group A to select the optimal keV. Then, the optimal keV in groups B, C and D was reconstructed and compared. Objective image quality, including vascular attenuation, image noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR), was evaluated. Subjective image quality was assessed using a 5-point Likert scale. In addition, the effective dose (ED), iodine load and iodine delivery rate (IDR) were compared between groups A and D. Results55 keV VMI was the optimal VMI in group B. The objective and subjective image quality of 55 keV VMI in group B were equal to or better than those of the CI in group A. The SNR, CNR and subjective image quality in group D were similar to those in group B (P>0.05). The ED, iodine load and IDR of group D were reduced by 44%, 59%, and 19%, respectively, when compared with those of group A. ConclusionsLow dose iodinated contrast material and radiation for 55 keV VMI in craniocervical CTA using SDCT could still provide equivalent or better image quality than the conventional scanning protocol.